COLOMBO, Sri Lanka – A top U.N. official appealed to Sri Lanka on Friday to begin a process of national reconciliation following its war with the Tamil Tiger rebels, but also cautioned that investigations into war crime allegations remain possible.

U.N. Secretary-General Ban Ki-moon was traveling Friday to Sri Lanka to discuss the conditions of nearly 300,000 ethnic Tamil civilians displaced by the war and to urge the government to work to heal the nation's ethnic divisions in the wake of the conflict, said his chief of staff, Vijay Nambiar.

The war broke out in 1983 with the Tamil Tigers demanding a separate homeland for the ethnic Tamil minority after decades of marginalization by the majority Sinhalese. In recent months, an intense government offensive forced the rebels to retreat from their strongholds in the north and cornered them along with tens of thousands of civilians along the northeast coast.

Ban sent Nambiar to Sri Lanka last week to press the government to pull back from its final offensive and allow the civilians in the war zone to escape. However, after he arrived, the military routed the rebels and killed their leader Velupillai Prabhakaran, effectively ending the war.

Prabhakaran's body was cremated and his ashes sent "into the air," said military spokesman Brig. Udaya Nanayakkara.

A total of 6,260 soldiers were killed in the latest round of fighting, which started in 2006, Nanayakkara said. The military said 22,000 rebel fighters were killed during the recent battles, though it was not clear how they arrived at that number.

Nambiar said the government now needs to hold discussions with Tamil leaders to pursue a political solution to their grievances.

"The process of national reconciliation, we feel, must be all-inclusive so that it can fully address the legitimate aspirations of the Tamils as well as other minorities," he said. "It is important that victory becomes a victory for all Sri Lankans."

International human rights groups accused the government of shelling the densely populated war zone in the closing months of the war, killing thousands of civilians. The government denied the accusation. The rebels were also accused of holding tens of thousands civilians against their will as human shields against the government offensive.

Nambiar said he was flown over the former war zone in a helicopter Thursday and saw below him a scene of mass devastation.

Vehicles on the ground were charred, trees were burned and closely clustered tent camps were badly battered, he said.

"We were not able to see any civilians. What was truly striking was almost the total absence of human habitation. ... It was almost eerie," he said.

Asked whether the United Nations planned to aid investigations into possible war crimes, Nambiar said the issue was expected to be discussed at the U.N. Human Rights Council next week.

"As far as the U.N. is concerned, where there are grave and systematic violations of international humanitarian law, these are things which should be looked at by the international community, by the United Nations," he said.

At a massive victory rally Friday, President Mahinda Rajapaksa made an oblique reference to suggestions that Sri Lankan leaders should be investigated for war crimes.

"Certain sections tried to put up hurdles" by trying to take him to an international tribunal, Rajapaksa said. "We had faith in the people, and we got down to this business, and were even prepared to go to the gallows."

The U.N. estimates at least 7,000 Tamil civilians were killed in the final offensive this year and between 80,000 and 100,000 people were killed throughout the war.

Nambiar said Ban plans to visit displacement camps in the north, fly over the former battlefield and meet with top officials in his brief visit.

His talks will focus on conditions in the camps, the possibility of swiftly resettling the displaced and the need for an urgent political settlement to the conflict, Nambiar said. Ban will also commend the government for defeating the rebels, who were branded a terrorist group internationally.

Sri Lanka said Thursday that it planned to return most of the displaced to their homes this year.

The U.S.-based group Human Rights Watch called on Ban to highlight the plight of the displaced, push for unrestricted access for aid workers to the camps and the former battlefield and call for the government to support an international commission of inquiry into violations of the laws of war by both sides.

Meanwhile, the International Committee of the Red Cross said it had been allowed to speak Thursday with three government doctors who ran an overwhelmed makeshift hospital in the war zone and were detained by the government on accusations they gave false information to the media about civilian casualties.

International human rights groups have demanded the government release the doctors and give them access to legal counsel.

"The ICRC saw them and spoke in private to them," said Red Cross spokeswoman Sarasi Wijeratne. She gave no details of their conditions.